1. Field of the Invention
The present invention relates to a diaphragm device.
2. Description of Related Art
Recently, monitor cameras (monitor CCTV cameras) are broadly used, for example, at financial-institution branches or locations and retail stores. The monitor camera is equipped with a lens unit (lens barrel) similarly to the usual camera. In the lens unit, a diaphragm device is arranged to regulate the amount of incident light. The diaphragm device is structured with precision components, including diaphragm vanes, a lever for moving the vanes, a driver device for electrically operating the lever (see, for example, JP-A-2003-233102).
However, in the event that vibration or an impact is applied to the diaphragm device, a component, e.g. the vane or the driver device, falls off the diaphragm device. Where such vibration or an impact is significant, the diaphragm device itself is possibly detached from the lens device.
Particularly, in a certain case, the monitor camera in its nature is possibly to be broken by a person who is not desired to be taken an image of by the monitor camera. For this reason, there is a need to improve the resistance to an impact force as compared to the usual camera.
In case the monitor camera is damaged at its diaphragm device, imaging is no longer available properly because of the impossibility to regulate the amount of light. In this case, the monitor camera is not allowed to exhibit its monitor function.